Prognostic factors for the success rate of embryo freezing.

  • Karlström P
  • Bergh T
  • Forsberg A
 et al. 
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To find some prognostic factors for the outcome of frozen-thawed cycles, we have retrospectively analysed all frozen pre-embryos that were thawed during 1993 and 1994 at two in-vitro fertilization (IVF) units in Sweden. Supernumerary pre-embryos were frozen from 551 oocyte retrievals and these resulted in 660 frozen-thawed cycles which lead to 623 thawed embryo transfers. The outcome of these transfers was 137 clinical pregnancies with a pregnancy rate of 22% per frozen-thawed embryo transfers. Women or =40 years, 19 and 5% respectively (P < 0.01). Transfers with two and three pre-embryos resulted in pregnancy rates of 23 and 27%, respectively, compared with 14% for transfer of one embryo. A pregnancy resulting from the initial embryo transfers had a predictive value for results of the subsequent frozen-thawed cycle. Embryo grade and cleavage stage at the time of freezing was important for the survival of the frozen-thawed pre-embryos. The pregnancy rate was not influenced by the cleavage stage, but a tendency toward a lower pregnancy rate was seen for the embryos with lower grading. To conclude, cryopreservation seems to be beneficial in women

Author-supplied keywords

  • Adult
  • Cleavage Stage
  • Cryopreservation
  • Embryo
  • Embryo Transfer
  • Female
  • Fertilization in Vitro
  • Freezing
  • Humans
  • Mammalian
  • Mammalian: cytology
  • Ovum
  • Ovum: cytology
  • Pregnancy
  • Reproductive Techniques
  • Retrospective Studies
  • Sweden

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  • P O Karlström

  • T Bergh

  • a S Forsberg

  • U Sandkvist

  • M Wikland

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